Machine for making well screens from metallic tubes



May 25,1926. 586,311

E. E. JOHNSON MACHINE FOR MAKING WELL SCREENS FROM METALLIC TUBES Filed March 5 1924 5 Sheets-Sheet l l 1* g E INVENTOR1 N m L... EYE. J'ormsolv. Q L?! BY 4 M IZMMA TToR/vEYa May 25 1926. 1,586,311 E. E. JOHNSON 'MACHINE FOR MAKING WELL SCREENS FROM METALLIC TUBES Filed March 3. 1924 5 Sheets-Sheet 2 17y vs lv TOR: E. E. Jbmvscw A TTORNEY May 2-5 1926.

'E. E. JOHNSON MACHINE FOR MAKING WE LL SCREENS FROM METALLIC TUBES Filed March 5 2 5 Sheets-Sheet 3 24 IN VEN TOR: E E. Jbmvso/v 5V V 94km; M4 fiL/Am A TTOFPNEYS May 25, 1926. 1,586,311

E. E. JOHNSON MACHINE FOR MAKING WELL SCREENS FROM METALLIC TUBES A T TQRNEY-s May 25 1926. I 1,586,311

E. E. JQHNSON MACHINE FOR MAKING WELL SCREENS FROM METALLIC TUBES Filed March 5. 924 5 Sheets-Sheet 5 15E. JOHNSON WW-M M/ MA A 7' TORNEKSI Patented May 25, 1926.

UNITED STATES EDWARD E. JOHNSON, OF ST. PAUL, MINNESOTA.

MACHINE FOR MAKING WELL SCREENS FROM MTETALLIC TUBES.

Application filed March 3, 1924. Serial No. 696,418.

My invention relates to machines for making well screens from metallic tubes. An object of the invention is to provide a machine which will operate upon a cylindrical metallic tube to make therefrom a well screen having a multiplicity of helically extending slots in its wall. In carrying out my invention, I provide a machine having means which give the metallic tube and a cutting tool a relatively combined rotative and longitudinal movement to produce a succession of helically extending slots in the wall of the tube, said slots extending around similar to a screw thread but with the ends of the slots separated by uncut portions, the length of the slots being preferably much greater than the distance between the ends of successive slots. In the construction shown, five slots are required to make a complete turn around the tube, and there will then be five uncut portions separating the ends of these slots so that the finished article will have five longitudinally extending posts to give it adequate strength. It is obvious that the number of slots per turn and hence, the number of posts, may be varied to suit tubes of dif ferent diameters, which result may be readily accomplished by varying the gearing of the machine. In the embodiment shown, the tube to be operated upon is clamped by a member which is constantly rotated and at the same time moved longitudinally to feed the tube to a cutting tool which is rotated at a high rate of speed and is reciprocated in a path transverse to the longitudinal axis of the tube, the timing arrangement being such that the period of engagement of the cutting tool with the tube is greater than its period of disengagement therefrom,

The full objects and advantages of my invention will appear in connection with the detailed description, and the novel features of my inventive idea will be particularly pointed out in the claims.

In the accompanying drawings which illustrate a practical form of construction in which my invention may be embodied, Fig. 1 is a side elevational view of the machine. Fig. 2 is an enlarged view in section on the line 2-2 of Fig. 1. Fig. 3 is a top plan v ew with a small portion in horizontal section. Fig. 4 is an enlarged view in section on the line 4-4 of Fig. 3. Fig. 5 is a View in section on the hue 55 of Fig 4. Fig. 6 is a view in longitudinal central section Fig. 7 is a detail plan view of a cutting tool support. Fig. 8 is a view in section on the line 8-8 of Fig. 7. Fig. 9 is a view in section on the line 9-9 of Fig. 7. Fig. 10 is a detail plan view of a member which cooperates with the cutting tool support shown in Fig, 7 and which is shown separated therefrom for the sake of clearness. Fig. 11 is a View in section on the line 11-11 of Fig. 10. Fig. 12 is a view in section on the line 1212 of Fig. 10. Fig. 13 is a view in section on the line 1313 of Fig. 6. Fig. 14 is a view in section on the line 1414 of Fig. 13 with the addition of a tube which constitutes the material to be operated upon, Fig. 15 is a view similar to Fig. 14 showing certain parts in a different position. Fig. 16 (Sheet; 2) is a fragmentary elevational View of the article produced in the machine. Fig. 17 is a view in section on the line 1717 of Fig. 3. Fig. 18 (Sheet 1) is a view in section on the line 1818 of Fig. 4.

Referring to the drawings, it will be seen that I provide a machine bed 20 which as best shown in Fig. 2 is troughlike. This bed is supported at one end by a standard 22 and at the other end by a structure 24 which constitutes a receptacle for a co0ling agent. The machine may be operated from any suitable source of power such as an electric motor 26 secured to the shaft of which is a large pulley 28 and a small pulley 30. The large pulley 28 is connected by a belt 32 with a small pulley 34 secured to the front end of a shaft 36, as best shown in Fig. 6. The small pulley is connected by a belt 38 with'a large pulley 40 secured to a shaft 42 mounted in bearings carried by the upper ends of standards 44 and 46. The shaft 42 has secured thereto a pulley 48 connected by a belt 50 with a pulley 52 secured to the shaft of a rotary pump contained in a casing 54 in communication with the receptacle 24. Secured to the shaft 42 is another pulley 56 connected by a belt 58 with a pulley 60 which will be referred to later. Secured to the shaft 42 is another pulley 62 connected by a belt 64 with a pulley 66 secured to the front end of a shaft 68 which, as shown in Fig. 3, is mounted in bearings 70 and 72. Secured to the rear of the shaft 68 is a large pulley 74 connected by a belt 76 with a small pulley 78 secured to a shaft 80 mounted in bearings 82 and 84 carried by a support 86 pivotally and adjustably mounted by pivot bolts 87 on brackets secured to the bed 20. Secured to the shaft is a saw 88 which is advantageously used in certain kinds of work. \Vhen work which does not require the use of the saw is being performed the support 86 carrying the saw therewith may be readily removed. The pulley 60 previously referred to is secured to a shaft 90 mounted in a support 92 carried by the bed and to this shaft is secured a pinion 94 meshing with a gear 96 loose on a shaft 98. A collar 100 is secured to the shaft 98 and this collar carries a slidable hand operable plunger 102 by means of which the gear 96 may be locked and unlocked with relation to the shaft 98. Provision for the latter condition is desirable in order that a clamping device hereinafter described may be readily retracted to initial position. Secured to the shaft 98 is a pinion 164 meshing with a gear 106 secured to a shaft 108 which at its forward end is mounted in a bearing on the support 92 and at its rear end is mounted in a bearing 109 carried by a member extending up from the bed 20. Secured to the shaft 108 is a disk member 110 which as shown in Fig. 4 has a depressed cam portion 112 extending for one-fifth of its circumference. A cam roller 113 is carried by an arm member 114 which as shown in Fig. 17 consists of two side portions spaced from each other. As will be apparent from Fig. 4, this arm member near one end thereof carries a pivot pin 115 upon which is mounted a square block 116 fitting slidably in a slideway 117 formed in an arm member 118. Instead of mounting the square block 116 directly upon the pin 115, I preferably mount it upon a Collar 119 through which the pin 115 passes as shown in Figs. 4 and 18. The collar 119 is longer than the block 116 and the pin 115 passes through slots in the two side portions of the arm member 114 so that when nuts on the ends of pin 115 are loosened, adjustment may be made in order that when the roller 113 rests upon the low portion of the cam disk 110, the arm members 114 and 118 will be in alinement with each other as shown in Fig. 4. It will be apparent from Fig. 18, that when the nuts on the ends of the pin 115 are tightened, the collar 119 will be clamped between the side portions of the arm 114 and the block 116 will be left free to turn on the collar as the block reeiprocates in the slideway 117 of the arm member 118. The outer end of the latter member surrounds and is secured to the front end of a tube 120 which is mounted for oscillatory movement in a cylindrical member or sleeve 122 which will be later referred to. The cam roller 113 is maintained in engagement with the periphery of the cam disk 110 by a coiled spring 124 attached at one end to a lug 126 carried by the arm member 118 and attached at its other end to a bolt 128 adjustably mounted in a bracket 130. The arm member 114 at its end opposite the end carrying the block 116 is provided with elongated openings 131 through which extends a pin 132 attached to the fixed support 92 as shown in Fig. 17. A bolt 134 has an eye 136 at the lower end thereof whichfits snugly around the pin 132. A stiff coil spring 138 surrounds the bolt 134 and this spring is interposed between caps 140 and slidably positioned on the bolt 134. The cap 140 rests upon the arm member 114 and the cap 142 at the upper end of the bolt may be adjusted by a nut 143 threaded on the upper end of the bolt. It will be apparent that when the cam roller 113 is lifted by the high portion of the cam 110 the arm member 114 will be rocked on the pin 132 as a pivot, and the arm member 118 will also be rocked on account of the block 116 having a sliding and pivotal movement in the slot 117. The spring 124 keeps the arm member 118 in the position shown in Fig. 4 in alinement with the arm member 114 when the roller is on the depressed portion of the cam 110, and, therefore, the tube 120 to which the arm member 118 is secured will be given an oscillatory movement through the operation of the cam. As will later appear, if the tube being operated upon presents a thick portion to the cutting tool support, the arm member 118 cannot be lifted as high as it is under ordinary conditions. In such case, the elongated openings 131 permit the outer end of the arm member 114 to rise in opposition to the tension of the spring 138, thereby decreasing the swinging movement of the arm 118 by a corresponding amount. The front end of the shaft 36 previously referred to is mounted in bearings 144 and 145 carried by a yoke-shaped member 146 pivoted upon a pin 148 mounted on a bracket 150. A second pin 152 mounted on this bracket passes through an enlarged opening in the member 146 so that the latter is permitted to have a slight rocking movement. A tube 154 is secured at its front end in an opening in the member 146, the bearing 145 being secured within this front end. The tube 154 is concentrically spaced from the shaft 36 and to its rear end is secured a hollow block 156 within which is a bearing 158 for the rear portion of the shaft 36. Slots 159 are provided between the block 156 and the tube 154 for passage of a cooling agent. Secured upon the rear end of the shaft 36 is a bevel gear 160 which meshes with a bevel gear 162 secured to the lower end of a spindle 164 carrying a cutting tool 166 at its upper end. The spindle 164 is l3 rotatably mounted in a block 168 which is screw-threadedly attached to the block 156. The latter block has flat vertical sides as shown in Fig. 8 and as shown in Fig. 9 one of these flat sides for a portion of its length is extended outwardly to produce an extension 170 which contains a dovetailed recess 172. hen the device is assembled, the straight vertical sides of the block 156 are slidably positioned between the straight vertical interior surfacesof two arms 174 extending from a member 17 6 secured to the rear end of the sleeve 122 previously referred to. The interior surface of one of the arms 174 is partly cut away to form a portion 178 within which the extended portion 170 of the block 156 fits. As will be apparent from Fig. 13, a tooth 180 extends longitudinally from the rear end of the tube 120. This tooth is a gear tooth in form and coacts with recess 172 as a rack so that when the tube 120 is oscillated by the operation of the cam disk 110, the tooth 180 is moved around from the position shown in Fig. 14 into that shown in Fig. 15, thereby causing the block 156 together with the block 168 attached thereto and carrying the cutting tool 166 to be moved vertically. hen the block 156 is thus moved upwardly. it is evident that the tube 154 and the shaft 36 supported thereby at its rear end will also move upwardly. This movement is permitted by the pivotal mounting of the yoke member 146. The sleeve 122 is exteriorly screwthreaded for the greater portion of its length and carries a nut member 182 to which is secured a large gear 184 which meshes with a small gear 186 feathered on the shaft 108. The gear 184 is rotatably associated with one end of a connecting bar 188 by means of a nut 189 screwed upon the nut member, and the gear 186 is rotatably associated with the other end of this bar by means of a quilled member 190. The ratio of the gear 186 to the gear 184 is 1 to 5 in the embodiment shown. One end of the nut member 182 is externally threaded to receive a clamping member 190 having an interior inclined surface for cooperation with the exterior inclined surface of a cooperating clamping member 191 whereby the tube T to be operated upon may be clamped for rotative and longitudinal movement with the nut member 182. A number of ringlike guide members 192 are secured to the bed 20, and these members have inwardly extending projections 194, such as shown in Fig. 6 so that the tube T is accurately guided for its rotative and longitudinal movement. The particular construction and manner of attaching the projections 194 constitutes no part of my invention. If desired, these projections may consist of parts left integral on the inside of ring members 192. The saw support 86 has a lug 196 attached thereto which at its outer end carries a cam roller 198 as shown in Fig. 2, and this cam roller engages a cam 200 which intermittently lifts the saw from engagement with the tube T. The saw when employed will operate in a manner to clean out or widen the slots which have been previously formed by the cutting tool. The belt 7 6 when permitted to do so by the depressed portion of the cam 200 acts to swing the saw support 86 so that the saw will move forwardly. The extent of this forward movement is determined by means of a stop member 201 secured to the support 86 and which comes into engagement with the end of a set screw 202 secured to the bed 20. When the saw is not to be used, the saw support 86 may be wedged in backward position, or may be removed from the bed. A pipe 203 controlled by a cock 204 leads from the pump casing 54, and as shown in Fig. 4, this pipe delivers into the space between the tubes 120 and 154 so that the cooling agent which is pumped passes rearwardly in this space and is delivered to the cutting tool through the slots 159. The cooling agent passes through the slots which are cut in the wall of the tube T and drops into the trough of the bed 20 which carries it forward for delivery through an opening 206 back to the receptacle 24. The pipe 203 is provided with a flexible portion 207 shown in Fig. 3 in order not to interfere with the rocking movement of the tube 120 to which its delivery end is attached. As shown in Fig. 6, the packing 208 prevents the cooling agent from escaping at the front end of the tube 120. This packing is held in place by a ring 210 loosely surrounding the tube 154 and secured to the hollow portion of the arm 118.

The operation and advantages of my invention will be readily understood in con nection with the foregoing description. The cutting tool 166 is driven at a high rate of speed 011 account of the shaft 30 having secured thereto a small pulley 34 driven by a belt 32 running over a large pulley 28 operated by the motor. The hollow block 156 and the attached block 168 constitute a support for the cutting tool spindle 164 and this support is reciprocated so that the cutting tool is caused to alternately advance and recede with relation to the tube by means of the tooth 180 engaging in the recess 172 in the block 156. As previously stated the tooth 180 extends rearwardly from the tubular member 120 which is caused to oscillate by means of the cam 110 and the connections between this cam and the forward end of said tubular member. As shown in Fig. 4, the high portion of the cam 110 extends for a much greater portion of the periphery of the disk than does the depressed portion of the cam. Hence, the period of engagement of the cutting tool with the tube being operated upon is much greater than its period of disengagement therefrom. The cam 110 is so designed that when the cam roller 113 is on the depressed portion thereof, the cutting tool will be completely disengaged from the tube T, and when the cam roller is on the high portion of the cam the block 168 carrying the cutting tool is in engagement with the interior surface of said tube. It is apparent, therefore, that if this tube presents a thicker place than usual to the cutting tool portion, the parts would be liable to be strained unless yielding movement is provided for. Such yielding movement is permitted by the spring 13 acting in connection with the elongated openings 131 in the arm member 114 as previously described in detail. The slots in the tube T are produced helically dueto the fact that the nut member 182 carrying the tube is operated in such manner as to give the tube a combined rotative and longitudinal movement. In the embodiment shown the gears 186 and 18% have a ratio of 1 to 5. and, hence, there will be five slots per turn of the tube. The cutting tool is tapered and, hence. the slots as indiated at S will be beveled so that they are wider at the inner surface of the tube than they are at the outer surface thereof. It is desirable that the slots shall be thus enlarged inwardly in order that any particles that may pass into the tube with the liquid will not be retained in the slots but will escape at the inside, thus preventing clogging of the slots. For some classes of work the cutting tool 164 alone will produce slots of the character desired. If it is desired to produce slots of greater width the saw 88 is employed. This saw as will be apparent from the previous description operates to cut into the slots which have just been formed by the cutting tool. In order that the nut member 182 and parts associated therewith may be readily returned to initial position for operation upon another tube, the disengaging plunger 102 is slid outwardly to unlock the gear 96 from the shaft 98. This allows the shafts 98 and 108 to rotate freely so that the nut member may be readily screwed back. This result may be accomplished by turning the nut member directly or by applying a wrench to the squared end of the shaft 98. It may some times become desirable to stop the reciprocating movement of the cutting tool support and the feeding movement of the tube without stopping the motor. This is easily and quickly accomplished by pulling out the plunger 102. By watching the position of the cutting tool, this plunger may be pulled so as to leave the cutting tool completely disengaged from the tube. It will be understood that the drive shaft, 36 and tubular member 15% swing up and down in a vertical plane upon the pin 148 as a. pivotal point, that the threaded member 122 is entirely stationary, and that the tubular memher 120 merely oscillates within the member 122 which in effect constitutes a bearing. The pump supplies a constant stream of cooling agent to the cutting tool, and to the saw when the latter is employed so that overheating of these parts is prevented. The cooling agent may consist of any liquid suitable for this purpose which -an be kept circulating by the pump.

I claim:

1. A machine for making well screens i'rom metallic tubes comprising a cutting tool, means for giving the tube and said cutting tool a relative combined rotative and longitudinal movement, and means for causing said cutting tool and tube to alternately approach and recede with relation to each other to produce a succession of helically extending slots in the wall of the tube.

2. A machine for making well screens from metallic tubes comprising means for giving the tube a combined rotative and longitudinal movement, a cutting tool, and means for causing said cutting tool and tube to alternately approach and recede with relation to each other to produce a succession of helically extending slots in the wall of the tube.

3. A machine for making well screens from metallic tubes comprising means for giving the tube a combined rotative and longitudinal movement, a rotatable cutting tool, and means for causing said cutting tool and tube to alternately approach and recede with relation to each other to produce a succession of helically extending slots in the wall of the tube.

4. A machine for making well screens from metallic tubes comprising means for giving the tube a combined rotative and longitudinal movement, a rotatable cutting tool, and means for causing said cutting tool to alternately advance and recede with relation to the tube to produce a succession of helically extending slots in the wall of the tube.

5. A machine for making well screens from metallic tubes comprising means for giving the tube a combined rotative and longitudinal movement, a rotatable cutting to the tube to produce a succession of helically extending slots in the wall of the tube, a sawpositioned to operate in the slots formed by said cutting tool, and means for causing said saw to alternately advance and recede with relation to the tube.

7. A machine for making well screens from metallic tubes comprising means for giving the tube a combined rotative and longitudinal movement, a rotatable cutting tool, means for causing said tool to alternately advance and recede with relation to the tube to produce a succession of helically extending slots in the wall of the tube, and means for supplying a cooling agent to said cutting tool.

8. A machine for making well screens from metallic tubes comprising a troughlike bed, means supported by said bed for giving the tube a combined rotative and longitudinal movement, a rotatable cutting tool, means for causing said tool to alternately advance and recede with relation to the tube to produce a succession of helically extending slots in the wall of the tube, a receptacle for a cooling agent, and a pump for pumping the cooling agent from said receptacle for delivery to said cutting tool, said trough-like bed being arranged to carry back to said receptacle the cooling agent which passes said cutting tool.

9. A machine for making well screens from metallic tubes comprising a stationary externally threaded cylindrical member, a nut member carried by said cylindrical member, a clamp carried by said nut member for holding the tube, means for rotating said nut member whereby the tube is given a combined rotative and longitudinal movement, a rotatable cutting tool, and means for causing said cutting tool to alter nately advance and recede with relation to the tube to produce a succession of helical extending slots in the wall of the tube.

10. A machine for making well screens from metallic tubes comprising a stationary externally threaded hollow cylindrical member, a nut member carried by said cylindrical member, a clamp carried by said nut member for holding the tube, means for rotating said nut member whereby the tube is given a combined rotative and longitudinal movement, a rotatable cutting tool which is inside said tube when the latter is being held by said, clamp, a slidable support for said cutting tool, and means for causing said support to reciprocate whereby said cutting tool produces a successlon of helically extending slots in the wall of the tube.

11. A machine for making well screens from metallic tube's comprising a stationary externally threaded hollow cylindrical member, a nut member carried by said cylindrica' member, a clamp carried by said nut member for holding the tube, means for rotating said nut member whereby the tube is given a combined rotative and longitudinal movement, a rotative cutting tool which is inside said tube when the latter is held by said clamp, a slidable support for said cutting tool, a cam, a tubular member within said cylindrical member and operatively connected with said cam for partial rotation thereby, and a tooth carried by said tubular member and engaging in a recess in said slidable support for reciprocating the latter whereby said cutting tool produces a succession of helically extending slots in the wall of the tube.

12. A machine for making well screens from metallic tubes comprising a stationary externally threaded hollow cylindrical member, a nut member carried by said cylindrical member, a clamp carried by said nut member for holding the tube, means for rotating said nut member whereby the tube is given a combined rotative and longitudinal movement, a rotatable cutting tool, a driven shaft extending through said cylindrical member for rotating said cutting tool, a cam, a tubular member within said cylindrical member and operatively connected with said cam for oscillation thereby, and connections between said tubular member and said cutting tool whereby oscillatory movement of said tubular member will cause said cutting tool to alternately advance and recede with relation to the tube to produce a succession of helically extending slots in the wall thereof.

13. A machine for making well screens from metallic tubes comprising a stationary externally threaded hollow cylindrical member, a nut member carried by said cylindrical member, a clamp carried by said nut member for holding the tube, a gear secured to said nut member, a gear meshing with said first mentioned gear, a shaft on which said second gear is feathered, a cam secured to said shaft, a cutting tool, a spindle upon which said cutting tool is mounted, a reciprocating support for said spindle, a driven shaft extending through said cylindrical member for rotating said spindle, a tubular member within said cylindrical member and operatively connected with said cam for oscillation thereby, connections between said tubular member and said spindle support whereby oscillatory movement of said tubular member will cause said cutting tool to alternately advance and recede with relation to the tube to produce a succession of helically extending slots in the wall thereof, and means for rotating said cam shaft.

14. A machine for making well screens from metallic tubes comprising a troughlike bed, a stationary externally threaded hollow cylindrical member supported on said bed, a nut member carried by said cylindrical member, a clamp carried by said nut member for holding the tube, a gear secured to said nut member, a gear meshing with said first mentioned gear, a shaft on which said second mentioned gear is feathered, a cam secured to said shaft, a cutting tool, a spindle upon which said cutting tool is mounted, a reciprocating support for said spindle, a driven shaft extending through said cylindrical member for rotating said spindle, a tubular member within said cylindrical member and operatively connected with said cam for oscillation thereby, connections between said tubular member and said spindle support whereby oscillatory movement of said tubular member will cause said cutting tool to alternately advance and recede with relation to the tube to produce a succession of helically extending slots in the wall thereof, means for rotating said cam shaft, a saw shaft, a saw secured to said shaft and positioned to operate in the slots formed by said cutting tool, means for swinging said saw shaft to cause said saw to alternately advance and recede with relation to said tube, a receptacle for a cooling agent and a pump for pumping the cooling agent from said receptacle to the space within said tubular member for delivery to said cutting tool, said trough-like bed being arranged to carry back to said receptacle the cooling agent which passes said cutting tool.

15. A machine for making well screens from metallic tubes comprising means for giving the tube a combined rotative and longltudlnal movement, a rotatable cutting tool operating within the tube, a support for said cutting tool, means for reciprocating said support to cause said cutting tool to produce a succession of helically extending slots in the wall of the tube, and means which permits yielding movement of said support relatively to the tube when said support comes into engagement with the tube.

16. A machine for making well screens from metallic tubes comprising means for giving the tube a combined rotative and 1011- gitudlnal movement, a cutting tool, a spindle upon which said cutting tool is mounted, a support for said spindle mounted for reciprocation within the tube, means for rotating said spindle, a cam, a tubular member operatively connected with said cam for 0scillation thereby, connections between said spindle support and tubular member whereby oscillatory movement of the latter will cause said cutting tool to alternately advance and recede with relation to the tube to produce a succession of helically extending slots, in the wall thereof, and means associated with the connections between said cam and tubular member whereby yielding movement of said support relatively to the tube is permitted when said support comes into engagement with the tube.

17. A machine for making well screens from metallic tubes comprising a stationary externally threaded hollow cylindrical member, a nut member carried by said cylindrical member, a clamp carried by said nut member for holding the tube, means for rotating said nut member whereby the tube is given a combined rotative and longitudinal movement, a cutting tool, a spindle upon which said cutting tool is mounted, a support for said spindle mounted for reciprocation within the tube, means for rotating said spindle, a tubular member oscillatingly mounted in said cylindrical member, connections between said spindle support and tubular member whereby oscillatory movement of the latter will cause said cutting tool to alternately advance and recede with relation to the tube to produce a succession of helically extending slots in the wall thereof, an arm secured to said tubular member, a second arm member having at one end thereof a slidable and pivotal connection with said first arm member, a fixed pivot for the other end of said second arm member extending through an elongated opening therein, a spring for resiliently holding the last mentioned end of said second arm toward said cam, and a cam roller intermediately mounted on said second arm for engagement with said cam, said spring in con junction with said elongated opening permitting yielding movement when said spindle support comes into engagement with the tube.

18. A machine for making well screens from metallic tubes comprising means for giving the tube a combined rotative and longitudinal movement, a cutting tool, means for rotating said cutting tool, means for causing said cutting tool to alternately advance and recede with relation to the tube to produce a succession of helically extending slots in the wall of the tube, and means whereby said first and third mentioned means may be stopped while said second mentioned means is allowed to run.

19. In a machine for making well screens from metallic tubes, a cutting tool, means for giving the tube and said cutting tool a continuous relative rotative movement, and means for causing said cutting tool and tube to alternately approach and recede from each other, to produce a succession of helical slots in the wall of the tube.

In testimony whereof I hereunto aifix my signature.

EDWARD E. JOHNSON. 

